Degradation of Prometryn During Uv/Persulfate Process: Kinetics and Disinfection By-Product Formation

Abstract

Prometryn is one of the commonly used triazine herbicides and is also widely used for the removal of algae in aquaculture. This work studied the degradation kinetics of prometryn by UV/persulfate (PS) oxidation and confirmed that it follows the pseudo-first-order kinetics, with the rate constant (kobs) being calculated as 0.2339 min-1. The effects of PS concentration, water matrix (background ions of Cl- and Br- and natural organic matter), and solution pH on prometryn degradation were assessed. It was found that the degradation rate of prometryn enhanced with increasing concentrations of PS, Cl-, and Br- but decreased with increasing NOM concentration and pH. Radical scavenging experiments confimed that both HO• and SO4-• promoted prometryn degradation in UV/PS, but SO4-• promoted it more significantly. When Br- is present in water, it can lead to the the formation of brominated disinfection by-products (DBPs), which are more carcinogenic and mutagenic than their chlorinated analogous. In sum, UV/PS process can effectively degrade prometryn but the generation of DBPs should be carefully controlled.

Keywords: Prometryn, UV/persulfate, kinetics, Contribution of radicals, Brominated disinfection by-products